German Patent No. 39 29 747 describes a method and device for controlling an internal combustion engine, where the time of the control during which pre-injection has occurred is ascertained. This ascertained, minimum time is used to correct the control.
In the case of a method and a device for controlling an internal combustion engine, where a control time of a partial injection is corrected on the basis of a comparison of a first variable to a setpoint value, in which case the first variable characterizes the curve of the partial injection, it is thereby possible to correct the pre-injection amount in a very precise manner during the operation of the engine. Errors that are based on manufacturing tolerances and/or aging effects of the engine and injection system may be compensated to the greatest possible extent. It is particularly advantageous that the procedure is not only implementable in particular operating states, but is also possible in nearly all operating states. In particular, a correction is possible in the case of different rail pressures, engine speeds, and loads.
It is especially advantageous when the first variable characterizes the start of combustion of the main injection. The ignition delay, i.e. the time between the start of combustion and the start of the corresponding injection, is an important variable that influences the noise emissions.
The correction is particularly advantageous in the pre-injection, since in this case, small deviations caused by tolerances have a large effect.
The evaluation of the signal of an ionic-current sensor has proven to be especially advantageous, since this signal effectively simulates the course of the combustion. In particular, the same applies to a combustion-chamber pressure sensor.
In addition to the signals of these sensors, variables derived from these sensors signals may also be used for the correction.